It is desirable for certain information to be processed in the order in which it is sent at one end and received at another end. For example, regarding stock purchases, if two customers place an order at a brokerage firm to buy stock from a stock market, it is desirable to have a first customer who placed a first order to have her purchase order of stock to occur before the second customer who placed a second purchase order. Given that the prices of stock fluctuate on the stock market and that purchase orders affect the price of stocks, and moreover, the timing of a purchase can have important financial consequences, the first purchase order of stock that is sent over some medium, such as the Internet, should be processed first, and the second order of stock should be processed second. Thus, the order or purchases should be preserved at one end (the stock market) when it arrives from some previous destination (the brokerage firm). This order preservation not only is desirable in the context of the stock market, but also applies to banking and other fields where information order preservation may be important.
Furthermore, not only is the preservation of information order important, but given the variety of transport media and their accompanying protocols, it is also desirable to be able to process information that is transmitted in different forms using a variety of different means. Put another way, it is desirable to be able to handle such information in a neutral manner, not relying on any specific transport medium or protocol. Thus, in one instance it may be desirable to use the Internet and hypertext transfer protocol (HTTP) to place a stock order, and in another instance it may be desirable to use a telephone system and its accompanying keypad to place a stock order. Even within a designated medium, such as the Internet, it may be more desirable to use one protocol over another, such as using file transfer protocol (FTP) over HTTP—for whatever desired reasons.
Given these goals and the complexity of information flow, error handling situations should to be addressed. In the case of stock orders, or more broadly, in case of any messages that are to be transmitted from one end to another end, if something goes wrong, handlers that deal with any arising problems should be in place to ensure that information flow does not break down and that information order is preserved.
These handlers need not only function correctly between two endpoints, but also in a distributed environment. In a distributed environment, where there may be dozens of servers and corresponding applications, error handling becomes especially complicated. Information can travel in various paths, and in case something goes wrong, it is often difficult to fix any desired transmittal and subsequent processing of such information. Thus, it would be desirable to have various error handling scenarios that are capable of functioning in a transport-neutral manner when information should be in-order while it is transmitted in a distributed environment.